title: A neocortical delta rhythm facilitates reciprocal interlaminar interactions via nested theta rhythms.
abstract: Delta oscillations (1-4 Hz) associate with deep sleep and are implicated in memory consolidation and replay of cortical responses elicited during wake states. A potent local generator has been characterized in thalamus, and local generators in neocortex have been suggested. Here we demonstrate that isolated rat neocortex generates delta rhythms in conditions mimicking the neuromodulatory state during deep sleep (low cholinergic and dopaminergic tone). The rhythm originated in an NMDA receptor-driven network of intrinsic bursting (IB) neurons in layer 5, activating a source of GABAB receptor-mediated inhibition. In contrast, regular spiking (RS) neurons in layer 5 generated theta-frequency outputs. In layer 2/3 principal cells, outputs from IB cells associated with IPSPs, whereas those from layer 5 RS neurons related to nested bursts of theta-frequency EPSPs. Both interlaminar spike and field correlations revealed a sequence of events whereby sparse spiking in layer 2/3 was partially reflected back from layer 5 on each delta period. We suggest that these reciprocal, interlaminar interactions may represent a "Helmholtz machine"-like process to control synaptic rescaling during deep sleep.
authors.affiliation: Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, United Kingdom.
authors.forename: Lucy M
authors.initials: LM
authors.lastname: Carracedo
authors.forename: Henrik
authors.initials: H
authors.lastname: Kjeldsen
authors.forename: Leonie
authors.initials: L
authors.lastname: Cunnington
authors.forename: Alastair
authors.initials: A
authors.lastname: Jenkins
authors.forename: Ian
authors.initials: I
authors.lastname: Schofield
authors.forename: Mark O
authors.initials: MO
authors.lastname: Cunningham
authors.forename: Ceri H
authors.initials: CH
authors.lastname: Davies
authors.forename: Roger D
authors.initials: RD
authors.lastname: Traub
authors.forename: Miles A
authors.initials: MA
authors.lastname: Whittington
mesh_terms: D000465:Algorithms; D000818:Animals; D003198:Computer Simulation; D003700:Delta Rhythm / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005110:Extracellular Space / Q000502:physiology; D017629:Gap Junctions / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology; D008959:Models, Neurological; D019579:Neocortex / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012894:Sleep Stages / Q000502:physiology; D013569:Synapses / Q000502:physiology; D013826:Theta Rhythm / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology